react-timer-mixin

Using bare setTimeout, setInterval, setImmediate and requestAnimationFrame calls
is very dangerous because if you forget to cancel the request before the
component is unmounted, you risk the callback throwing an exception.

If you include TimerMixin, then you can replace your calls to
setTimeout(fn, 500) with this.setTimeout(fn, 500) (just prepend this.) and
everything will be properly cleaned up for you.